how to use moldflow adviser for better warpage and ovality results

[Anonymous]

Hi,

I recently started using moldflow adviser and still in beginner level.

If i run analysis for some round part as shell or bowl what are the parameters to take care for getting better results for ovality.

I tried to tweak mold temperature and melt temperature results seem to be similar.

for basic understanding can you help me with how to start for single cavity and multiple cavity can runner and gate directly created in moldflow advisor.

Can you share some case study and link to start with topic.

Regards,

Nilesh

[mppkumar]

Hi @Anonymous

welcome to Moldflow family

Please go thru the below links for basic understanding on single & multi cavity modeling and runner system modeling.

Single cavity modeling

http://help.autodesk.com/view/MFAA/2017/ENU/?guid=GUID-0C8ED9EA-205D-405C-9247-71ED3128663F

multi cavity & Family mold

http://help.autodesk.com/view/MFAA/2017/ENU/?guid=GUID-1DA81B9C-A8DB-428C-B9BA-81CA93B451EB

Please go thru the below links for modeling gates & runners

http://help.autodesk.com/view/MFAA/2017/ENU/?guid=GUID-9E07097B-4669-45B1-AA52-CAA31ED4B772  (runner creation using wizard)

http://help.autodesk.com/view/MFAA/2017/ENU/?guid=GUID-650F0B0C-9FC6-43BF-AC1D-62851DFFE23A

Gate location plays major role in controlling the warpage; can you share some images on your component with predicted warpage?

Hope above links are helpful to you

[bernor_mf]

Hi Nilesh,

just to add to the good information provided by @mppkumar

In Adviser UI click tab Start & Learn

There you have Tutorials and Videos.

Videos has Essential skills, with model a single-cavity mold and multi-cavity mold.

Link to: Moldflow tutorial models

ASMA is Autodesk Simulation Moldflow Adviser

By this you have close reach of the basics.

Regards,

Berndt

[Anonymous]

Hi Team,

i was running through analysis for one part.

The result what i am getting for the war page are not good what possible gating option can be suggested and processing parameter.

would like to improve results material used is PA66 GF30%.

[bernor_mf]

Hi,

it is difficult to give recommendations on a single picture and no model.

Is the issue related to fiber orientation or difference in volumetric shrinkage?

Now, to understand what contributes most the deflection , Deflection, all effects result, review the differential results:
Deflection, differential cooling
Deflection, differential shrinkage result
Deflection, orientation effects

Deflection, all effects result
The Deflection, all effects result combines differential cooling, differential shrinkage and orientation effects to show the final part warpage.

Deflection, differential cooling
The Deflection, differential cooling result shows the final part warpage due to uneven cooling.

Deflection, differential shrinkage result
The Deflection, differential shrinkage result shows the final part warpage due to the variation in shrinkage across the part.

Deflection, orientation effects
The Deflection, orientation effects result shows the final part warpage due to the material orientation throughout the part.
If the material is fiber filled, this corresponds to the fiber orientation in the part.

If no cooling circuits and Cool analysis, it is 0 (might show very low numbers theoretically)

So main contributors are :
Deflection, differential shrinkage result
Deflection, orientation effects

Now, as PA66+GF30%, it is probably Deflection, orientation effects, causing the main issue.
The fibers often takes over when aroun 20- 25%
But you should review each results to be sure, and to know how to improve.

Contributors to warpage

Reducing warpage due to differential shrinkage
The main ways of influencing differential shrinkage effects are:
Designing packing profiles.
Reducing part thickness variations.

Reducing warpage due to orientation effects
The three main ways to influence orientation (apart from choice of material) are to change:
Molding conditions.
Model thickness.
Gate locations.

When you know main contributor to warp, you can focus on how to resolve issue.

Hope this helps.

Regards,

Berndt

[Anonymous]

wall thickness is not major issue

I have attached picture for fiber orientation and differential shrinkage.

Is gating suitable i have tried center gate but results remain same

[bernor_mf]

Hi,

from differential shrinkage and orientation effects, differential shrinkage seems to contribute most.

Check your packing profile, that pressure level and time is sufficient.

(default is packing pressure 80% of injection pressure, and 10s)'

Look at Time to reach ejection temperature result plot, to get an understanding of how long packing time can be.

The Time to Reach Ejection Temperature result plot also guide how long time packing pressure can be applied.
It is a bit below Transition temperature, so a little bit shorter packing time could be applied probably.

Background/reason:

Time to freeze is depending on the Transition temperature, Ttrans, in material details tab Rheological properties.
This is the freezing temperature for material.

Time to reach ejection temperature result plot is base on Ejection temperature in material details tab Recommended Processing.
So, basically, the time when part could be ejected.

As lower temperature, it will take longer to reach ejection than freeze.

Hope this helps.

Regards,

Berndt

[Anonymous]

Hi bernor,

As you explained i have checked my packing profile and it was default.

Time required for ejection i have try to show image.

As you suggested i have tried to check material processing recommendation.

And set mold temperature 95 and melt temperature as 300.

Material 70G33L NC010

How much packing pressure needs to change.

can you check and share your feedback would like to get results under 0.5mm

Regards,

Nilesh

[Anonymous]

Hi bernor,

As you suggested i have check the packing profile is default.

Ejection time required i am attaching a image.

I have changed the mold temperature and melt temperature still no improvement in results.

I have selected 70g33L NC010 material.

Can you check and revert with solution for right way to getting minimum warpage.

would like to control under 0.5mm.

Regards,

Nilesh

[bernor_mf]

Hi Nilesh,

I will download model and I will have a look on the model you shared.

Do some analysis and see if I can give you some advice.

Kind Regards,

Berndt

[bernor_mf]

Hi Nilesh,

made simulation as shown in pictures with 2 gates.

First: Used Design Adviser to review thickness:

Warp - Cause of Deflection:

Main contribution is differential shrinkage. Orientation effects do contribute too.

As the gates are on thin area of rim, gate on thin thickness area – Time to reach ejection temperature shows rim will freeze off earlier than overall general part thickness, causing packing problem, which means high volumetric shrinkage and probable warpage problem and dimensional issues.

Rim will freeze off earlier than overall general part thickness,
Inner area will continue to shrink more
This will bend the thinner outer rim, as it cannot resist the forces

Next steps to test:
- Gate in thicker thickness region
- Increase packing pressure and packing time

Further: Review part design - can changes be made to improve to design for manufacturing and application?

Different restrictions due to part and mold design might not make optimum gate position possible.
Look for best compromise, with Moldflow Design Principles in mind.

Will do some more simulations and update.

Regards,

Berndt

[Anonymous]

Thanks Bernor,

For taking time and giving the solution.

Can we create thick section near the gating area purposely so that it might work for possible gating.

Gating in center is not good idea for glass filled fiber as it might not give uniform fiber distribution.

As you have shown ejection time 32s.

how much packing needs to be applied in parameter considering ejection time.

If design cannot be improved how much minimum we can obtain through processing.

Do you think adding cooling lines and doing analysis will improve the results.

Can you share processing parameter considered during analysis.

Regards,

Nilesh Nagare

[bernor_mf]

Hi Nilesh,

replies on your questions:

Can we create thick section near the gating area purposely so that it might work for possible gating.
> Yes, I believe so. This is many times done, to ensure an open channel for packing.
Make a small redesign, and a simulation to verify.

Gating in center is not good idea for glass filled fiber as it might not give uniform fiber distribution.
> Okay. But you can use simulation to test different options.

As you have shown ejection time 32s.

> yes the maximum is about 32s - but around 12s in 3 mm thickness area

how much packing needs to be applied in parameter considering ejection time.
> about 12s in 3mm thickness region.

The Time to Reach Ejection Temperature result plot also guide how long time packing pressure can be applied.
It is a bit below Transition temperature, so a little bit shorter packing time could be applied probably.

Background/reason:

Time to freeze is depending on the Transition temperature, Ttrans, in material details tab Rheological properties.
This is the freezing temperature for material.

Time to reach ejection temperature result plot is base on Ejection temperature in material details tab Recommended Processing.
So, basically, the time when part could be ejected. As lower temperature, it will take longer to reach ejection than freeze.

For packing in Adviser, using the Time to reach ejection temperature result plot and investigating times in gating area is a good way

to find maximum time to pack.

Now, depending on difference between Transition temperature and Ejection temperature, you could change Ejection temperature to a value

closer to Transition temperature if you wish to fine tune times. But initially not necessary, I would say. 

If design cannot be improved how much minimum we can obtain through processing.
> Basically nothing... main cause is differential shrinkage and orientation effects, and if you cannot change to pack the part,
well then you are stuck.

Do you think adding cooling lines and doing analysis will improve the results.
> First fix main cause, then test cooling.
In simulation we want to have a big processing window for production, and not narrow it in design stage.

Can you share processing parameter considered during analysis.
> Sure.
As time to reach ejection temperature is about 12s in 3 mm thickness I used 12s packing time.

Some materials has measured Shrinkage Properties.
This could help to understand pressure level and volumetric shrinkage
Zytel 70G33L NC010 : DuPont Performance Polymers has it, and 2 points for 3mm.
So I decied to go for a mid value, 60 MPa packing pressure.
The volumetric shrinkage should then be around 4-5%

Automatic for injection time, switch over and cooling time.

Regards,

Berndt

[bernor_mf]

Hi Nilesh,

Gate in 3mm thickness area
Gate on same side , but in 3mm thickness area
Packing 60MPa for 12s

The part is now flatter – so an improvement.
Main contributor to deflection is now orientation effects
Middle bend is shrinkage and orientation effects

Add some results comparing different gate positions.

To conclude:
Gate on thicker area (redesign if needed)
Ensure sufficient packing pressure and packing time

Next steps:
Add runners and cooling to verify when first improvements completed.

Regards,

Berndt

[Anonymous]

Thanks Bernor,

For quick  response

It helped me to get more clarity on the topic and also new learning each day.

Appreciate your efforts in sharing knowledge.

Regards,

Nilesh Nagare

[bernor_mf]

You are welcome, Nilesh.

I am happy to help and share (when time permits  )

If you have time, there is more of it:

https://www.youtube.com/user/autodeskmoldflow 

Regards,

Berndt